It is known from U.S. Pat. No. 3,759,984 to prepare succinic acid and/or derivatives thereof by reacting ethylene with carbon monoxide and an alcohol in the presence of a palladium compound having a strong scid residual group, an amino acid, and a heavy metal salt while supplying oxygen to increase the reaction rate and to prolong the catalyst life. The examples of this known process show that dimethyl succinate was obtained in a low yield, calculated on starting ethylene.
It is an object of the present invention to prepare diesters fo dicarboxylic acids in a very high yield.